(A)bort? (R)etry? (F)ail?
On a different note, never underestimate the value of a modal dialog that gives you a chance to retry an IO operation that failed. Loose USB cables and network shares over Wifi can make those happen a lot more often.
My understanding today is that one of them(fail?) gives the application a chance to do something clever. Did any application actually handle this gracefully? Something like, Disk 11/15 error(fail) Please put in recovery parity disk.